Potencial remineralizante y resistencia al ataque ácido del péptido P11-4, nanohidroxiapatita, silicato de calcio/fosfato de sodio y barniz de fluoruro sódico en esmalte bovino desmineralizado

Resumo

Background The formation of dental caries is a dynamic process, with several cycles of demineralisation and remineralisation alternating throughout the day in the oral cavity. This will depend on various factors such as bacterial biofilm, tooth structure and dietary sugars, as well as environmental, genetic and salivary influences on the individual. Damage to dental enamel, mainly dental caries, has a direct impact on people's quality of life, not only because of the physical pain and functional limitation that it entails, but also because of its impact on the psychological and social level when there is aesthetic affectation; therefore, it is important to carry out strategies to strengthen and remineralise dental enamel. Objectives The general objective of the project is to determine the possible remineralising capacity and resistance to acid attack of four dental materials used on previously demineralised bovine enamel using a cyclic pH system. Method An experimental in vitro study was carried out using a model of demineralisation in bovine teeth using a demineralising solution pH (4.4), followed by remineralisation (pH 7.0) using 4 remineralising agents (P11-4 peptide (Curodont® Protect), nanohydroxyapatite (Orthocare nHAp®), calcium silicate/sodium phosphate (Regenerate Enamel ScienceTM) and sodium fluoride varnish (Duraphat® 2.26% F) subjected to pH cycling (22 hours of remineralising solution and 2 hours of demineralising solution) for 30 days. A total of 160 samples were randomly distributed into 8 experimental groups and were previously demineralised with lactic acid for 72 hours, except for the intact enamel group. Subsequently, surface microhardness, microanalysis of enamel mineral content (Ca, P, C, O, F, Na, Mg, Si, Cl) together with high-resolution imaging (SEM/FESEM) roughness analysis and external topography by AFM. Results The initial microhardness values obtained were similar in the experimental groups, except for the demineralised enamel, which was lower (p < 0.001). The most resistant to the demineralisation/remineralisation cycles, with the lowest loss of microhardness was Positive Control (Duraphat), followed by Regenerate and Negative Control. Curodont Protect had lower values than Duraphat and Regenerate, but higher values than Orthocare and Intact Enamel. The least resistant were demineralised enamel and Orthocare (p < 0.001). Regarding the microanalysis of the mineral content, the demineralised enamel group had the lowest concentration of Ca, P, C, F, Si, Cl and obtained significant differences with the rest, the highest concentration of F was found in Duraphat followed by Regenerate (p < 0.001). As for Ca, the values were homogeneous. Regenerate had the highest P content followed by Curodont P. The highest Si concentration was found in Regenerate, followed by Orthocare (p < 0.001). Morphological analysis showed a surface with calcium fluoride deposits in the Duraphat, Regenerate and Curodont Protect groups. However, Orthocare showed numerous pores and intercrystalline spaces. The roughness analysis showed that Duraphat had the highest surface roughness, followed by Curodont + Fluor and Orthocare. Orthocare and Regenerate had the lowest roughness. Conclusions The results of this study have shown that in terms of microhardness analysis, the Duraphat group was more resistant, followed by Regenerate; Curodont Protect and finally Orthocare, presenting lower values than intact enamel. Regarding the final mineral content after the demineralisation process, variations were observed in the experimental groups, with Duraphat having the highest F content and Regenerate the highest P and Si content. All the groups have undergone modifications in the morphology of the enamel, with Orthocare standing out as the group with the lowest calcium fluoride deposit and the highest Duraphat deposit. As for roughness, the highest value was detected in Duraphat and the lowest in Curodont P and Regenerate, interpreted as a sign of remineralization.